Microvascular Decompression for Oculomotor Nerve Palsy due to Nonaneurysmal Vascular Compression

BACKGROUNDDiabetes mellitus and aneurysmal compression are well-known causes of oculomotor nerve palsy (ONP), but nonaneurysmal vascular compression of the oculomotor nerve has rarely been reported. CASE DESCRIPTIONA 70-year-old nondiabetic man presented with left ONP for the past 2 days. Magnetic resonance imaging revealed the left posterior communicating artery to be compressing the left oculomotor nerve. Microvascular decompression of the offending artery from the nerve via a left frontotemporal craniotomy was performed; the nerve showed a color change suggestive of degenerative alteration. ONP was fully resolved within 1 month of surgery. CONCLUSIONSWhether nonaneurysmal vascular compression of the oculomotor nerve is a true cause of ONP is sometimes controversial. However, recent developments in magnetic resonance imaging can clearly demonstrate the spatial relationship between the oculomotor nerve and vessels. Detailed magnetic resonance imaging should be used to diagnose compression of the oculomotor nerve by blood vessels. Microvascular decompression is the treatment of choice in this situation.